“I am now looking forward to evolving under this fantastic coach and alongside so many great teammates.”

Added Chelsea FC Technical Director Michael Emenalo: ‘Tiemoue was outstanding as Monaco emerged as one of Europe’s best sides last season and we are delighted to welcome him to Chelsea.”

‘Despite his young age he already has plenty of experience as a French title winner and having competed in the latter stages of the Champions League, we believe he will add considerable quality to our squad.’

The contract is reportedly for five years with a transfer fee of £40m, making the Frenchman the most expensive midfielder in Chelsea history and the second priciest player overall. Tops is the £50m Stamford Bridge shelled out to acquire Fernando Torres from Liverpool in January of 2011.